Family members Maria Rodriguez, 58, Issac Briseno, 12, and Ailyn Miguel, 12, all of La Puente, died after their car was struck as it sat on a freeway shoulder after experiencing mechanical problems, according to the California Highway Patrol.

Jose Prieto, 60, of Rialto, who was driving a Toyota Tacoma and stopped to help the family, also was killed.

California Highway Patrol Officer Jesus Garcia said Maria Briseno, of La Puente, was driving a Honda sedan eastbound on the 10, west of Citrus Avenue in Fontana around 12:30 p.m. when it began to overheat, so she pulled onto the right shoulder.

After the car was stopped, Luis Sanchez, of Riverside, drove his Nissan Frontier onto the shoulder, striking a man and woman who were standing outside the stranded vehicle, Garcia said in a news release.

The Nissan continued forward, striking the rear of the Honda and pushing it into the rear of Prieto’s Toyota Tacoma, causing the Toyota to veer left across traffic lanes and into the center divider.

The family members who died were passengers inside the Honda, Garcia said.

Sanchez and Maria Briseno were both taken to Arrowhead Regional Medical Center in Rancho Cucamonga.

The cause of the crash is still under investigation, Garcia said. On Friday, he said it was unknown whether either alcohol or drugs were a factor in the crash.

Craig Shultz reports on communities in Riverside County, primarily Hemet, Menifee, Perris and San Jacinto. A journalist for more than three decades, he has reported on everything from sports to city halls and schools. He was previously the editor of The Hemet News and The Valley Chronicle. Shultz was born and raised in the San Fernando Valley area of Los Angeles and graduated from Cal State Northridge.